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Airborne and ground reconnaissance of part of the syenite complex near Wausau, Marathon county, Wisconsin

Trace Elements Memorandum 742

This report concerns work done on behalf of the Division of Raw Materials of the U.S Atomic Energy Commision
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Abstract

Airborne and ground reconnaissance for radioactive minerals in part of the syenite complex near Wausau, Marathon county, Wis., found 12 radioactive mineral localities. The rocks in the area are of Precambrian age and consist of syenite and nepheline syenite, which have intruded older granite, greenstone, quartzite, and argillite. There are very few outcrops, and much of the bedrock is deeply weathered and covered by residual soil. Thorium-bearing zircon pegatite float was found within the area of syenite and nepheline syenite at four localities. Reddish-brown euhedral to subeuhedral crystals of well-zoned zircon (variety cyrtolite) comprise more than 40 percent of some of the specimens. The radioactive mineral at four localities outside the area of syneites was identified as thorogummite, which occurred in nodular masses in residual soil. Alinement of the thorogummite float and associated radioactivity suggests that the thorogummite has resulted from weathering of narrow veins or pegmatites containing thorium-bearing minerals. Unidentified thorium-bearing minerals were found at three localities, and a specimen of allanite weighing about 2 pounds was found at one locality. Shallow trenches at two of the largest radioactivity anomalies showed that the radioactive material extended down into weathered bedrock. The occurrences might warrant additional physical exploration should there be sufficient demand for thorium. Further reconnaissance in the area would probably result in the discovery of additional occurrences.

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Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Airborne and ground reconnaissance of part of the syenite complex near Wausau, Marathon county, Wisconsin
Series title:
Trace Elements Memorandum
Series number:
742
Year Published:
1955
Language:
English
Publisher:
U.S. Geological Survey
Description:
Report: 23 p.; 1 Plate: 17.01 x 16.95 inches
Country:
United States
State:
Wisconsin
County:
Marathon County
City:
Wausau
Additional Online Files(Y/N):
Y